Wireless phones, laptops, PDAs, base stations and other systems may wirelessly transmit and receive data. A single-in-single-out (SISO) system may have two transceivers in which one predominantly transmits and the other predominantly receives. The transceivers may use multiple data rates depending on channel quality.
An MR×MT multiple-in-multiple-out (MIMO) wireless system, such as that shown in FIG. 1, uses MT transmit antennas 104 at a first transceiver 100 and MR receive antennas 106 at a second transceiver 102. First and second transceivers 100, 102 in FIG. 1 are designated “transmitter” and “receiver”, respectively, for the purposes of illustration, but both transceivers 100, 102 may transmit and receive data.
The multiple antennas 104, 106 may improve link quality (e.g., achieving a minimum bit error rate (BER)) by using a transmission signaling scheme called “transmit diversity,” where the same data stream (i.e., same signal) is sent on multiple transmit antennas 104, after appropriate coding. The receiver 102 receives multiple copies of the coded signal and processes the copies to obtain an estimate of the received data.
The multiple antennas 104, 106 may achieve high data rates by using another transmission signaling scheme called “spatial multiplexing,” where a data bit stream may be demultiplexed into parallel independent data streams. The independent data streams are sent on different transmit antennas 104 to obtain an increase in data rate according to the number of transmit antennas 104 used.